Immunoglobulin G (IgG) is part of the immune system response found in blood. If an infection, toxin or foreign body of any kind is detected in the blood stream, the body reacts by pushing IgM (Immunoglobulin M) to the area affected. IgM is the largest antibody. It works to start the healing and recovery process. In the meantime, when IgM responds IgG production quickens. Together with other immunoglobulins, IgG works to basically get rid of the problem. - See more at: http://www.babymed.com/laboratory-values/immunoglobulin-g-igg-serum-during-pregnancy#sthash.lvaqOf6e.dpuf